The present invention relates generally to acoustic filters and sound absorbers for air conditioners, and more specifically to a ductless noise attenuator for reducing noise while minimizing constriction of the air flow
Air conditioners are becoming more essential for providing temperature control for equipment and personnel. Unfortunately, air conditioning systems produce noise as well as temperature controlled air, and a variety of noise suppression systems have historically been developed. Exemplary in the art are the noise suppression systems of the following U.S. patents, which are incorporated herein by reference:
U.S. Pat. No. 1,816,769, issued to E. Fisk on July 28, 1931;
U.S. Pat. No. 4,068,736, issued to Dean et al on Jan. 17, 1978;
U.S. Pat. No. 4,164,265, issued to E. Kucharczyk on Aug. 14, 1979;
U.S. Pat. No. 4,362,223, issued to I. Meier on Dec. 7, 1982;
U.S. Pat. No. 2,973,703, issued to W. Jack on Mar. 7, 1961;
U.S. Pat. No. 2,853,147, issued to D. D'Eustachio on Sept. 23, 1958; and
U.S. Pat. No. 4,336,836, issued to S. Satomi on June 29, 1982.
The systems cited above have a common characteristic in that they separate the air conditioner from the recipient by a system of ventilators or ducts. While these ducts transmit sound as well as air, the sound is reduced by baffles, gratings, and sound absorbing materials which line the ducts. For example, U.S. Pat. No. 1,816,769 (Fisk) discloses a sound suppressing ventilator which includes a plurality of angulated louvres for effecting sound attenuation. U.S. Pat No. 4,165,265 (Kucharczyk) discloses a sound attenuating baffle, which is positionable within a sound-absorbing ventilator, and wherein the baffle includes a plurality of angulated members for directing sound in various desired directions. U.S. Pat. No. 4,362,223 (Meier) discloses a sound absorbing device positionable within a fluid flow channel, the device including a plurality of angulated members for reflecting and absorbing sound.
While the ventilator constrictions described in the cited references are certainly effective, they are both expensive and tend to constrict the air flow from the air conditioner. In view of the foregoing discussion, it is apparent that there currently exists the need to reduce the noise from air conditioning units while minimizing the restriction of the air flow from these units. The present invention is intended to satisfy that need.